Cell Phones Interfere Barely with Medical Equipment

In their most recent analysis of cellular telephones and medical equipment, Mayo Clinic researchers report that the telephones tested did not interfere with medical devices that were more than three feet away, marking an improvement.

In the current study, 44 percent of the devices recorded some interference from the cellular telephones but the vast majority of this interference should not have had any significance for the patient.

“Technology changes in both cellular telephones and medical equipment may continue to mitigate or may worsen clinical-relevant interference,” says David Hayes, M.D., chair, Division of Cardiovascular Diseases, Mayo Clinic Rochester and one of the study’s authors who has tested equipment in previous studies. “Periodic testing of cellular telephones to determine their effects on medical equipment will be required.”

Sixteen different medical devices were tested and interference occurred in seven (44 percent). The researchers conducted 510 tests by holding the phone next to the devices and then rotating it once a call was received from a wired telephone. The cellular phones were placed near vulnerable sites on the device, such as serial ports, cable connection ports and displays.

The farthest distance away that a device was affected was 32 inches. Most interference occurred with devices that display electrocardiographic (ECG) or electroencephalographic (EEG) waveforms and involved noise interference.

ECG tracings represent the electrical activity of the heart, i.e., each heartbeat has a corresponding electrical event and is represented on the tracing, and the EEG tracing represents electrical activity of the brain. Two ventilator devices also experienced interference.